Edge grinder



Feb. 12, 1935. A. J. HOLMAN EDGE GRINDER 2 Sheets-Sheet 1 Filed Feb. 7, 1930 zuulnuu u m 1935- A. J. HOLNiAN EDGE GRINDER 2 Sheets-Sheet 2 Filed Feb. 7, 1930 jzverzib A 4444,, A '7 7Z5; W80

Patented Feb. 12, 1935 UNITED STATES PATENT QFFICE EDGE GRINDER Arthur J. Holman, Bro'okline, Mass. Application February 7, 1930, Serial No. 426,690 2' Claims. (01. 51' 1o1 My invention relates to grinders for accurately grinding in one operation the periphery of any object to any shape other than a circle and it has been the special object of my invention to provide an apparatus which is particularly adapted accurately to contour the edge of a lens sector such as is employed in the revolving lens discs shown in my United States Patent No. 1,584,098 of May 11, 1926.

My device may be best understood by reference to the accompanying drawings in which Fig. 1 is a front view of my device with the lens and its adjacent supporting parts shown in longitudinal cross section.

Fig. 2 is a cross sectional view on line 22 of Fig. 1, showing the master cam and its adjustably mounted stop.

Fig. 3 shows front and side views of a gauge which may be conveniently used for testing the work of the grinding apparatus to ascertain whether it has been so adjusted as to produce a contour identical iii size with that of the master cam.

Fig. 4 is a cross section on line 4 4 of Fig. 1 showing the face of the lens chuck.

Referring now more specifically to the drawings, 1 is a base frame which may be mounted on the table which supports the grinding wheel 2. The base frame 1 carries integral bosses 3 and 4 within which are press fitted sleeves 5 and 6 which serve as hinge pins for hinge bosses 7 and 8 which are integral with the oscillating frame 9. A drive shaft 10 passes through the sleeves 5 and 6 and is further supported by an outboard bearing 11 which is integral with the base frame 1. A driving pulley or gear 12 indicated by dotted lines may be mounted fast upon the shaft 10 and suitably connected with the driving system for the grinding wheel 2, so as to effect a reduction of speed of rotation of the drive shaft 10.

Arms 13 and 14 rising from the oscillating frame 9 carry respectively in integral bosses 15 and 16 the cam shaft 17, whereon is fast mounted the master cam 18, having an integral hub 19 secured by a pin 20 to the cam shaft 17. A chuck supporting sleeve 21 having an integral hub 22 is secured to the cam shaft 17 by the pin 23. A pin 24 is fast mounted in a boss 25 in the lowerpart of the chuck supporting sleeve 21.

An arm 26 rising'from the oscillating frame 9 mean integral boss 27 which has an outwardly projecting portion 28. Slidably mounted within the boss 27 is ajsleeve 29f within which is mounted the rotatable shaft 30. A second sleeve 31 is slidably mounted on the exterior of the projecting portion 28 of the boss 27 and is provided with a spiral slot 32 through which passes a pin 33 which is screwed in the projectingipo'rtion 28 of the boss 27. Press fitted into the end of sleeve 31 is a bushing 34. A handle 35 is fixed in the sleeve 31 and bushing 34. l

A gear 36 is fast mounted on sh'aft 30. and meshes with gear 37 fast mounted on shaft 10'. A gear 38 like gear 36 is fast mounted on shaft 17 and meshes with a gear 39 fixed on shaft 10 and indentical with gear 37, Shafts 17 and 3Q are in alignment, and their respective gear drives are such that there is no relative angular displacement during the operation of the device.

A lens chuck 40 is provided with a sleeve extension 41 which fits within the chuck support ing sleeve 21. The lens chuck 40 is provided with a hole within which the pin 24 may enter so as to retain the chuck 4D in proper alignmentwith the master cam 18. This arrangement permits removal of the work from the a'pparatus'for the purpose of gauging the contour, and the replacing of the work, exactly centered and correctly oriented with respect to the master cam, should further slight grinding be requiredl The lens 42 may be attached to the face of the chuck 40 by the usual application of pitch. It will be uhderstood, of course, that when using the device for contouring lens sectors of the sort appearing in my said patented device, the positiolj'of the lens on the chuck is so adjusted that its optical center falls on the axis of the sleeve extension 41 of the chuck 40. This centering of the work on the chuck is performed before the chuck is inserted in the chuck supporting sleeve 21.

A pressure plate 43 is'fast mounted on the shaft 30 and is provided with an integral hub 44 against which abuts one said coil spring abutting against an end of the sleeve 29. Attached to the sure plate 43' is a felt pad 46. r e

To the post 47 on the top of boss 16 may be; attached suitable means for yiel'dably holding the lens, or other object to be contoured, in contact with the grinding wheel 2. I

Integral with the base 1 and extending toward the shaft 48 of the grinding wheel 2" (see Fig.2) is a bracket 49 in whichjis mounteda pivot pin 50 which fits closely within a nple" in the frame 51. A stop 52 56 and 57, which posts are end of a ccil'spring 45, which surrounds shaft 30', the other end of surface of the pres s m u t u 'iany adjustable stop supporting means, comprising end members 53 and 54 connected by od-s55; press fitted intoend members 53 and 54 and are slidably mounted within holes in the frame 51. The end member 53 carries the stop 52 which is held thereon by the screws 53. The stop 52 is provided with a stop surface 59 the curvature of which is identical with the curvature of the grinding wheel 2. The stop 52 is so positioned with respect to the post 56, that the plane tangent to the stop surface 59 at its middle point, is normal to the axis of the post 56.

The post 56 is threaded to receive a knurled adjusting nut 60 and a lock nut 61 which may abut respectively against the bosses 62 and 63 within the frame 51.

An aligning arm 64 is attached to the top of the frame 51, and is so constructed that, when the spacing block 65 is placed between the shaft 48 of the grinding wheel 2 and the surface 66 on the end of the arm 64, the axis of the post 56, if extended, will intersect the axis of the shaft 48 at right angles. When the frame 51 is in this position, it may be there retained by means of the screws 67 which pass through slots 68 in the bracket 49 and enter threaded holes in the frame 51.

The operation of my device is as follows:

The base 1 with its attached parts is first set up on the table of the edge grinder and carefully aligned so that the shaft 10 is parallel to the grinding wheel shaft 48. When so positioned the device may be secured to the table by screws entering through the screw holes 69 (Fig. 1). The gear or pulley 12 is then suitably connected so as to be driven from the grinding wheel shaft 48 at a substantially reduced rate of speed.

The lens 42 is then mounted on the face of the chuck 40 and the chuck is placed in position in the chuck supporting sleeve 21. In order to place the chuck 40 in this position, it is necessary to retire the pressure plate 43 which may be done by pulling forward the handle 35 which moves the sleeve 31 and the shaft 30 to the left because of the bearing of the pin 33 against the side of the spiral slot 32, as the sleeve 31 is rotated. After the lens chuck 40 is in position, the pressure plate 43 is returned to the normal operative position shown in Fig. 1.

In order that the lens, when ground, may correspond in size and contour with the master cam 18, it is necessary to position the stop 52 in such a way that its surface 59, which has the same curvature as the grinding wheel 2, shall coincide with the projected surface of the grinding wheel 2 should that surface be extended to a position opposite the master cam 18. This is accomplished by so placing the stop that the radius which bisects the cord of the arc of the stop surface will pass through the axis of the grinding wheel shaft 48. To thus locate the stop the screws 67 are loosened and the block 65 is inserted between the shaft 48 and the surface 66 on the end of the arm 64. The screws 67 are then set up so as to fix the position of the frame 51 and the block 65 is removed. The knurled adjusting nut 60 and the lock nut 61 are then manipulated so as to set the stop supporting means in such position that the distance from the stop surface 59 to the axis of the shaft 48 is equal to the radius of the grinding wheel 2.

The oscillating frame 9 is then swung so as to bring the edge of the lens into contact with the grinding wheel and it is there yieldably held by suitable means attached to the post 47. It will be readily apparent that as the device is set in motion, the approach of the edges of the lens to the grinding wheel will be limited at all positions by the contact of the master cam against the stop so that continued grinding will result finally in the production of a lens having the same edge contour as the master cam both with respect to shape and size.

The accuracy of the adjustment of the stop 52 may be tested by inserting a finished lens in the gauge 70 which fits exactly the master cam 18. If the lens fits loosely within the gauge, the stop 52 should be moved slightly outward, and if the lens does not enter the gauge, the stop should be slightly retired.

It will be readily apparent from the foregoing that work of great precision may be done by means of my device, and that various edge contours may be obtained by variously shaping the master cam. As the cam is shaped exactly like the final form sought to be obtained for the product, it is apparent that the designing of the cam is greatly simplified and hence accuracy is more readily obtained. The employment of a stop, the surface of which corresponds in curvature, and alignment with the surface of the grinding wheel permits this convenient type of master cam.

When the master cam has fiat surfaces as illustrated, it is apparent that the point of contact between the master cam and the stop surface, travels over an arc of considerable length on the face of the stop, hence it is essential to provide a stop surface of greater arcuate length than is required for edging circular or elliptical work. Moreover, since the stop surface is unusually long, it is necessary to provide precise adjusting means to insure exact coincidence of the stop surface with an imaginary surface corresponding to an extension of the grinding surface of the wheel. Unless the stop surface is coincident with the wheel surface extended, the finished work cannot be true to the master cam.

Having thus fully described my invention, what I claim is:

1. In an edge grinder the combination of a rotatably-mounted shaft, means whereon an object to be ground may be fast mounted on said shaft, a master cam fast mounted on said shaft, and contoured to the size and shape of the object to be produced, a circular grinding wheel, a pivotally and adjustably mounted frame, an adjustable cam stop supporting means slidably mounted in said frame, a cam stop carried by said cam stop supporting means and provided with a cam stop surface having the same curvature as said grinding wheel, means for adjusting the angular position of said pivotally mounted frame in a manner whereby the surface of the cam stop may be symmetrically positioned with respect to the axis of said grinding wheel and means whereby said shaft is rockably mounted to swing toward and away from said grinding wheel and cam stop.

2. In an edge grinder the combination of a rotatably-mounted shaft, means whereon an object to be ground may be fast mounted on said shaft, a master cam fast mounted on said shaft and contoured to the size and shape of the object to be produced, a circular grinding wheel, a shaft whereon said grinding wheel is mounted, a pivotally and adjustably mounted frame, an adjustable cam stop supporting means slidably mounted in said frame, a cam stop carried by said cam stop supporting means and provided with a cam stop surface having the same curvature as said grinding wheel, means for adjusting the angular position of said pivotally-mounted frame in a manner whereby the surface of the cam stop may be symmetrically positioned with 5 respect to the axis of said grinding wheel, said means comprising an arm projecting from said frame to a position above said shaft whereon said grinding wheel is mounted and a. removable spacing block, and means whereby said first-mentioned shaft is rockably mounted to swing toward and away from said grinding wheel and cam stop.

ARTHUR J. HOLMAN. 

